Since the discovery of Norfloxacin, improvements have been added to synthetic quinolone antimicrobial agents in antimicrobial activity and in pharmacokinatics, and many compounds have been launched for clinical use as a chemotherapeutic agent effective on all most all systemic infectious diseases.
However, low sensitive bacteria resistant to the synthetic quinolone antimicrobial agents have recently been increasing in the clinical field. For example, bacteria resistant to drugs other than synthetic quinolone antimicrobial agents have come to acquire resistance to synthetic quinolone antimicrobial agents, as exemplified by Staphylococcus aureaus insensitive to β-lactam antibiotics (MRSA). Therefore, more effective drugs have been keenly demanded in the field of clinics.
Further, it has been revealed that synthetic quinolone antimicrobial agents tend to involve side effects, such as induction of convulsion in a combined use with a non-steroid antiinflammatory agent, and phototoxicity. Therefore, development of safer synthetic quinolone antimicrobial agents has been sought.